GlaxoSmithKline, Vir target emergency authorization for intramuscular COVID-19 antibody drug with new trial win

GlaxoSmithKline GSK House in Brentford, UK
As Vir Biotechnology CEO George Scangos, Ph.D., noted, the trial was conducted when the delta variant was at its height. (GlaxoSmithKline)

GlaxoSmithKline and Vir Biotechnology’s COVID-19 antibody drug sotrovimab already bears an FDA emergency use authorization (EUA) as an infusion. Now, the pair hopes to win the same status for an intramuscular formulation.

The latest plan comes as a phase 3 trial showed sotrovimab, also known as Xevudy, delivered similar efficacy between intramuscular and intravenous administration routes in nonhospitalized mild to moderate COVID patients who are at high risk of disease progression.

The IM administration group recorded a 2.7% rate of progression to hospitalization for over 24 hours or death through Day 29 of the trial versus 1.3% in the IV arm, the two companies reported Friday from the COMET-TAIL study. The adjusted difference of 1.07% falls within the noninferiority bar GSK and Vir previously set with the FDA.

As Vir George Scangos, Ph.D., noted, the trial was conducted when the delta variant was at its height and a big proportion of trial enrollment was done in Florida, an infection hot spot where hospitalization rates hit over 10% among confirmed cases.

GSK and Vir have previously demonstrated in lab dishes that sotrovimab remained active against 14 coronavirus variants including delta.

RELATED: GSK and Vir, navigating early antibody pitfalls, tout delta variant-busting data for latecomer sotrovimab

The latest COMET-TAIL study had its own setback; while the current success is for 500-mg IM sotrovimab, the trial originally had a 250-mg arm but was terminated early after an independent data monitoring panel noticed a high rate of hospitalizations.

Sotrovimab in its 500-mg infusion form won FDA EUA in May for mild to moderate COVID disease. Final analysis from the COMET-ICE study showed the antibody drug reduced the number of patients who died or required hospitalization by 79% over placebo when given within five days of symptom onset. The new COMET-TAIL trial tested sotrovimab with a wider treatment window of up to seven days post-symptoms.

IM sotrovimab could be looking at a potential competitor in AstraZeneca’s IM COVID antibody cocktail AZD7442. Last month, the AZ therapy showed in its own trial that it could reduce hospitalization or death rate by 67% when given to mild to moderate patients within five days of symptom onset.

RELATED: Despite Merck's oral COVID-19 drug, antibodies by Regeneron, GSK and others still have billions in sales ahead: analyst

AZ’s current EUA request for AZD7442, filed in early October, is for prophylaxis use to prevent symptomatic COVID.

Intramuscular injection would be a more convenient administration route, but Regeneron’s COVID combo REGEN-COV already has an EUA for an under-the-skin formulation, which is authorized for use within three days of a positive COVID test.

The antibody drugs may have a smaller market now that Pfizer is seeking FDA EUA for its oral antiviral Paxlovid after the compound cut the risk of hospitalization or death by 89% in high-risk nonhospitalized patients. The treatment window was three days post-symptoms, but Pfizer said the drug showed similar results when given within five days of symptom onset.

Despite the convenience and big efficacy showing of oral antivirals, SVB Leerink analyst Geoffrey Porges recently noted that antibodies might have a role to play in the prevention market and may have an edge for treating people longer into a symptomatic infection.